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Author Topic: Backlash not applied during manual JOG?  (Read 10642 times)

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Offline dude1

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Re: Backlash not applied during manual JOG?
« Reply #30 on: January 21, 2016, 01:32:03 PM »
that's nasa speck

Offline Banr

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Re: Backlash not applied during manual JOG?
« Reply #31 on: July 11, 2016, 08:13:34 PM »
As completely off topic as this thread went, does anyone know if they ever implemented Backlash comp for the ESS??? and as far as properly built machines not needing it, I work on $3 million dollar, Fanuc controlled multi spindle CNC machines for a living...and every single axis has Backlash compensation.

Offline rcaffin

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Re: Backlash not applied during manual JOG?
« Reply #32 on: July 11, 2016, 10:06:01 PM »
Fanuc controlled multi spindle CNC machines
Yeah, well, old machines with Fanuc controls probably do have backlash ... >:D

Cheers
Roger

Offline Banr

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Re: Backlash not applied during manual JOG?
« Reply #33 on: July 11, 2016, 10:09:44 PM »
Lol, They're brand new, Installed 5 of them this year already.

Offline dude1

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Re: Backlash not applied during manual JOG?
« Reply #34 on: July 11, 2016, 10:10:58 PM »
Banr yes it can be done it is a hell off a lot of work yes it does work but for a single person it will be from 10 to 100 hours, there is so much involved in getting it working the average person it's in the hard basket  

Offline Banr

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Re: Backlash not applied during manual JOG?
« Reply #35 on: July 11, 2016, 10:13:59 PM »
huh? Getting the software to work, or setting back lash comp, cause that takes 30 seconds.
« Last Edit: July 11, 2016, 10:22:38 PM by Banr »

Offline dude1

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Re: Backlash not applied during manual JOG?
« Reply #36 on: July 11, 2016, 10:56:11 PM »
getting it to work as intended at any speed at any position on the table, sure flick a switch what is the backlash amount in the first places say it is 0.001 at x100 and 0.005 at x300 what is it

Offline Banr

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Re: Backlash not applied during manual JOG?
« Reply #37 on: July 11, 2016, 11:13:40 PM »
Backlash comp is there to take up 0.0001" to 0.002" of slop in the mechanics, ie leadscrew and nut, ballscrews. bearing preload, belt stretch, motor coupler tolerances. these things do not vary over the course of axis travel, Any mechanical mechanism has to have some varying degree of tolerance, "backlash" if it didn't, it would be welded tight and not move. If you have different amounts of backlash over different portions of axis travel, then you have have different problems, that can only be corrected by replacing the defective component. generally your leadscrew or ballscrew, or worst case scenario, your ways, or linear rails are wore out.

Offline rcaffin

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Re: Backlash not applied during manual JOG?
« Reply #38 on: July 12, 2016, 12:09:28 AM »
Any mechanical mechanism has to have some varying degree of tolerance, "backlash" if it didn't, it would be welded tight and not move.
Strictly speaking, that is not really true. You could have ball bearings with zero backlash. They might wear a bit more quickly of course. Such an idea is readily available, as double opposing angular contact bearings. As featured in many good lathe headstocks for instance.

Now, elasticity - that's a different matter. You could have zero backlash but some compliance due to elasticity, and it would then be a question of machining forces affecting tolerances. However, you could not use conventional 'backlash correction' for this case. In most cases such effects might not matter in practice, but when diamond machining large optics to lamba/10, it does.

Such fun.
Cheers
Roger

Offline Banr

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Re: Backlash not applied during manual JOG?
« Reply #39 on: July 12, 2016, 12:12:27 AM »
touche sir, touche